The present invention is broadly concerned with an apparatus and method for forming, quick freezing and harvesting tissue from the margins of a tumor specimen, while preserving the anatomical orientation of the specimen. More particularly, it is concerned with an apparatus having a base, movable walls and a cover which may be adjustably intercoupled to frame a form for receiving and shaping an amorphous tissue specimen into a planar-surfaced block. The device further includes structure for freezing the specimen to a predetermined optimum temperature, so that the specimen will retain its shape for cutting after the form is removed.
Biopsy, or surgical removal of a tissue specimen for histologic examination, is frequently employed in order to establish a precise diagnosis. When a lesion is known or suspected to be malignant, the entire mass is typically excised, if possible, and an examination technique is often employed in which the tumor margin surface area is examined. This technique involves microscopic screening of the exterior surface area of the tumor for the presence of malignant cells to ensure that all such cells have been removed. If practiced effectively, tumor margin surface area examination enhances the likelihood of complete removal of all cancerous cells of a localized malignancy. Where removal of the malignancy was not complete, the method may be used to precisely identify the location of any residual malignancy for subsequent removal or, where that is not possible, for radiation therapy.
Once harvested, the tissue is frozen using, for example, the methods and devices set forth in Applicant's previous U.S. Pat. Nos. 4,695,339; 4,752,347; 5,628,197; 5,829,256; and 6,094,923, which patents are incorporated herein by reference, and the tissue is then sectioned into thin layers. The tissue is preferably snap frozen at a controlled rate in order to obtain a high quality frozen section which is not marred by voids and artifacts which might impair examination and diagnosis. Following dissection from the tumor, the tissue margin surfaces may also be further examined by methods such as electron microscopy.
In order to be effective, the technique of tumor margin surface area examination must include microscopic examination of the entire surface margin of the excised tumor. Moreover, the anatomical orientation of the tissue must be maintained throughout the procedure so that the surgeon may return to a specific source area of the tumor margin surface in order to excise additional tissue until histologic examination indicates that only healthy cells remain.
One of the problems associated with preparation of specimens for this method of histologic examination is that the tissue is normally excised in irregular shapes. Many tumors, such as breast cancer, are amorphous because they are comprised of fatty tissue. Anatomical orientation of the specimen is difficult to maintain when sectioning such specimens that are obtained, for example, in a lumpectomy for breast cancer.
It is difficult to conduct a thorough examination of the tumor margin surfaces in all planes because of the irregular geometric shape of such tumors. For example, a thin, planar surface slice of a round mass only effects a very small area of the total surface. That is, each thin section obtained by conventional methods from a tumor mass reveals only a portion of the tumor margin. However, the number of sections which can be examined microscopically is limited by practical considerations, such as time and availability of equipment and it is very difficult to orientate the excision position from an area where a large number of specimens were obtained.
It is important that the histologic examination be performed quickly, since the patient must be kept under anesthesia pending the microscopic evaluation, in case any additional tissue must be excised. For this reason, it is normally not possible to process large numbers of tumor margin surface sections in an effort to perform a completely thorough pathologic examination.
In order to obtain slices from the entire tumor margin surface area, it has been found to be expedient to form the tissue specimen into a polyhedron block having plane surfaces. Harvesting of the tissue from all of the resulting planar surfaces of the block serves to ensure that the entire tumor margin surface area has been harvested for examination. Because the block presents a limited number of such plane surfaces (six), the procedure can be conducted fairly quickly.
While it is important to form the entire excised tumor mass into a block, not all tumor masses are of the same size or shape, and many do not present bilateral symmetry. Although some tumor masses can be formed into a cube-shaped block having right angles or a rhomboid block having opposed complementary acute and obtuse angles at the vertices, there is a need for a form which can be adjusted to accommodate eccentric masses, which may lack parallel sides and angular symmetry.
In order to speed the examination process, the specimen must be quickly frozen to a predetermined temperature which will permit the tissue to retain a structured form. The specimen must then be promptly released from the form for harvesting of the tumor margin surfaces.
The apparatus and method of the present invention are specifically designed to quickly form and freeze an amorphous or eccentric specimen into a shape having a limited number of planar surfaces which are easily sectioned for rapid microscopic evaluation of the entire tumor margin.